> “Today it's quite easy…”

Not sure if you’re responding to my confusion (“Having difficulty imagining this constraint”).

I’m not asking about implementation of a solution nor of capability, but how the maxim “use what you make” is envisaged by the authors as a mechanism of engagement, management and quality for the IndieWeb. Why is it a pilar?

I'm not in the authors' heads, but I suppose they want to enhance the feeling of belonging.